Baby's tummy is measuring 2 weeks ahead. What can I do?

I am currently 28wks 4 days. I know that this might sound stupid but is there something I can do more for the baby's tummy to stop being two weeks ahead?

I was tested for gestational diabetes and passed - but barely (borderline). I'm monitoring my glucose levels by trying to eat the best way I can but still baby's tummy (only tummy) is measuring two weeks ahead. I'm even going on daily walks of about 20 mins.

Gynae told me that even though it's still early, if her tummy remains this way we would have to deliver via C-section. I would like to honestly avoid that. Is there anybody that passed through the same experience? Is there something else that I can maybe do?

Thank you